The present invention relates to a microdevice and a method of delivering or withdrawing a substance through the skin of a patient, and in particular to a method and device for withdrawing or delivering a substance such as a drug intradermally to a patient. The invention also relates to a device for enhancing the penetration of a microneedle array.
Various devices have been proposed for the intradermal sampling and delivering of substances such as pharmaceutical agents and drugs. Although subcutaneous sampling and delivery methods using a cannula are effective for many applications, the pain normally induced by the cannula has prompted the development of less painful delivery methods.
The skin is made up of several layers with the upper composite layer being the epithelial layer. The outermost layer of the skin is the stratum corneum that has well known barrier properties to prevent molecules and various substances from entering the body and analytes from exiting the body. The stratum corneum is a complex structure of compacted keratinized cell remnants having a thickness of about 10-30 microns. The stratum corneum forms a waterproof membrane to protect the body from invasion by various substances and the outward migration of various compounds.
The natural impermeability of the stratum corneum prevents the administration of most pharmaceutical agents and other substances through the skin. Numerous methods and devices have been proposed to enhance the permeability of the skin and to increase the diffusion of various drugs through the skin in order to be utilized by the body. According to some methods and devices, the delivery of drugs through the skin is enhanced by either increasing the permeability of the skin or increasing the force or energy used to direct the drug through the skin.
Other methods of sampling and delivering various substances through the skin form micropores or cuts through the stratum corneum. By piercing the stratum corneum and delivering a drug in or below the stratum corneum, many drugs can be effectively administered. In a similar manner, some substances can be extracted from the body through cuts or pores formed in the stratum corneum. The devices for piercing the stratum corneum generally include a plurality of micro-needles or blades having a length to pierce the stratum corneum without passing completely through the epidermis. Examples of these devices are disclosed in U.S. Pat. No. 5,879,326 to Godshall et al.; U.S. Pat. No. 5,250,023 to Lee et al., and WO 97/48440.
The above-noted devices include micron-sized needles or blades and can be effective in delivering or sampling substances in the body. However, these needles and blades have a length of a few microns to a few hundred microns and typically do not penetrate the skin to a uniform depth. The natural elasticity and resilience of the skin often results in the skin being deformed by the needles rather than pierced. Therefore, when a microneedle array is pressed against the skin, the outermost needles penetrate the skin while the innermost needles do not penetrate the skin or only penetrate to depth less than the outermost needles.
As a result, the prior methods and devices for the intradermal sampling and administering of substances have exhibited limited success. Accordingly, a continuing need exists in the industry for an improved device for the sampling and administering of various drugs and other substances to the body.
A method and device for the intradermal sampling or delivery of a substance though the skin of a patient is provided. A method of manufacturing and assembling a device for intradermally delivering or withdrawing a substance through the skin of a patient is also provided. In particular, a method and apparatus for delivering a pharmaceutical agent, such as a drug or vaccine, into or below the stratum corneum of the skin to a sufficient depth where the pharmaceutical agent can be absorbed and utilized by the body is provided.
According to an exemplary embodiment of the invention, a microdevice interface is provided. The interface comprises a body having a top face and a bottom face. The bottom face has first and second surface areas. The first surface area is raised from the body with respect to the second surface area. A recess is defined in the first surface area on the bottom face. An opening is defined in the body for fluid flow for into and out of the body.
In a further embodiment, the recess is in fluid communication with the opening and the body and is adapted to receive a skin penetrating device.
In another exemplary embodiment, a device for intradermally delivering or withdrawing a substance through at least one layer of the skin of a patient is provided. The device comprises a body having a bottom face, a top face spaced from the bottom face, a side edge, and a width. The body has a height which extends between the top face and the bottom face and which is less than the width. A channel in the body extends from the side edge and has an axis which preferably extends substantially parallel to the bottom face. A skin penetrating device is coupled to the bottom face and is in fluid communication with the channel.
According to another exemplary embodiment, the device comprises a body having a top face, a bottom face and a side edge. The bottom face has a first surface area lying in a first plane and a second surface area lying in a second plane. The first surface area is spaced outwardly from the second surface area. At least one skin penetrating member extends from the first surface area of the bottom face and is oriented to penetrate the surface of the skin of the patient.
In another embodiment, the device comprises a body having a top face, a bottom face, and at least one side edge. A skin penetrating member is coupled to the body and extends outward from the bottom face. The bottom face has a first surface area surrounding the skin penetrating member. The first surface area also includes a leak indicator for indicating leakage from the device.
A method for delivery or withdrawal of a substance through at least one layer of the skin of a patient is also provided. The method comprises the steps of: providing a device having a body with a bottom face having at least one skin penetrating device, a first surface area surrounding the at least one skin penetrating device and lying in a first plane, and a second surface area lying in a second plane. The first surface area is spaced outwardly from the second surface area. The at least one skin penetrating device is positioned on a target site of the skin of the patient. Pressure sufficient for the skin penetrating device to penetrate the skin and for the second surface area to contact the skin is applied against the device. A substance is then delivered to the target site and to the patient.
Accordingly, a method and device for intradermal sampling or delivery of a substance is provided. The method and device can allow for penetration of the skin for sampling or delivering a substance through the skin, substantially without pain to the patient. The structure of the device provides a low profile and an increased comfort level to the patient. Additionally, the device may easily be manufactured as a single piece by injection molding.
The advantages and other salient features of the invention will become apparent from the following detailed description which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.